Mechanical adjustment means for electrical limit switches

ABSTRACT

A mounting means for a positionable mounting plane with respect to a fixed base plane permits selective translation and space separation adjustments over a limited range. Translation is effected by a first lead screw means imparting limited pivot action about the axis of a second lead screw mounting means. Adjustment of the second lead screw effects separation by deflection of the member defining the mounting plane.

United States Patent [72] inventor Winston F. Williams Cedar Rapids, Iowa 121 1 ApplfNo. 33,019 [22] Filed Apr. 29, 1970 [45] Patented July 27, 1971 [73) Assignee Collins Radio Company Cedar Rapids, Iowa [54] MECHANICAL ADJUSTMENT MEANS FOR ELECTRICAL LIMIT SWITCHES 12 Claims, 5 Drawing Figs.

[52] US. Cl 200/47, 74/110, 200/153 LA, 200/166 M [51] lnt.Cl l'l0lh3/42 [50] Field of Search ..200/45, 153 LA, 153 T, 166 M; 74/1 10 [56] References Cited UNITED STATES PATENTS 2,505,225 4/1950 Akroyd 200/166 M X 2,640,891 6/1953 Buck et al v 2,837,616 6/1958 .laidinger 200/166 M 2,964,601 12/1960 Stockwell 200/153 '1' X 2,968,710 1/1961 Horberg 200/153 LA 3.099,735 7/1963 Roeser 200/166 M 3,192,350 6/1965 Horberg 200/47 X 3,210,519 10/1965 Kerchoff 200/47 X I 3,291,953 12/1966 Luik 200/172 A 3,472,977 10/1969 Ziegler 200/47 3,540,305 11/1970 Sprung 200/153 T X Primary ExaminerRobert K. Schaefer Assistant ExaminerWil1iam .1. Smith Attorneys-Richard W. Anderson and Robert J. Crawford ABSTRACT: A mounting means for a positionable mounting plane with respect to a fixed base plane permits selective translation and space separation adjustments over a limited range. Translation is effected by a first lead screw means imparting limited pivot action about the axis of a second lead screw mounting means. Adjustment of the second lead screw effects separation by deflection of the member defining the mounting plane.

PATENTE D JUL27 I97! 3' 5964M 7 sum 2 or 2 INVENTOR. WINSTON F. WILL/Ans AGENT precisely defined mechanical position extremes. Such a device might, for example, be employed in a servo mechanism for automatic control of an aircraft wherein, for numerous reasons, the linear excursion of the ram or drive rod of the servomust be precisely limited.

The object of the present invention is accordingly the provision of a simple and positive means for adjusting a pair of electrical limit switches such as microswitches with respect to a.

linearly positioned actuating cam member as might be carried on a servo ram member in a linear drive servo mechanism such that first and second precise physical positions of the ram member corresponding to respective ram position limits will effect actuation of the respective ones of the pair of microswitches.

A further object of the present invention is the provision of a simple mounting means for a positionable mounting plane with respect to afixed base plane which permits selective translation and space separation adjustments over a limited adjustment range in an exacting yet inexpensive manner.

The present invention is featured in the provision for a direct and positive means of precisely adjusting a pair of microswitches having fixed space separation in concertabout a path along the drive position axis of a linear actuating cam mechanism and additionally in concert about an axis transverse the drive axis of the cam member to arrive readily at the proper positioning of the microswitcli pair with respect to the linear actuating cam for coincidence between defined cam. position limits and respective switch actuations.

The present invention is further featured in the provision of mounting means for a space separated switch pair which include first and second screw adjustment means and a third motion-locking adjustment means permitting a pair of electrical limit switches to be positioned with respect toan actuating cam first for symmetry of switch actuation with respect to desired first and second mechanical limits of the cam actuator mechanism, and second for the proper convergence or divergence of switch-actuating points to obtain precise actuation of each of the switches at the defined limit positions of the actuating cam member. These and other features and objects of the present invention will become apparent upon reading the following description with reference to the accompanying drawings in which:

FIG. l is a functional diagram of a typical electrical limit switch function as it relates to a linear drive mechanism;

FIG. 2 is a diagrammatic representation of defined first and second defined cam position limits and the effect of symmetry and convergence-divergence adjustments in accordance with the present invention;

FIG. 3 is a front view of an electricallimit switch-adjusting mechanism in accordance with the present invention;

FIG. 4 is a side view of an cmbodimcntof electrical limit switch mounting and adjustment means in accordance with the present invention; and

FIG. 5 is a pictorial view of the limit switch-mounting means of the present invention. The basic problem and solution to which the present invention is directed is depicted functionally in FIG. 1. FIG. I illustrates first and second switches I0 and II which might comprise microswitches including respective actuating members 13 and 14. Switches and II are carried on a common mount member 12 so as to define a fixed space separation between the first and second switches,

and thus the switch-actuating members 13 and 14. The pair of switches 10 and 11 might be utilized in conjunction with a linear actuating cam 16 carried on a ram or rod member 15, the latter comprising the driven member of a servo or actuator mechanism 17.

The actuator mechanism 17 and rod member 15 might comprise respective components of a linear drive servo mechanism. For a particular application such as an aircraft control, first and second precisely defined mechanical limits as to the extreme positioning possible for the ram member 15 may be necessary. It is common in such applications to include electrical limit switches by means of which the power effecting the drive of the ram member by energization of the actuating mechanism is removed when the extreme limits are reached.

Microswitches I0 and 11 depicted in FIG. 1 are commonly employed as limit switches. These microswitches might be respectively actuated as their actuating members 13 and I4 ride up the linear cam surfaces of the member 16 which projects from, or is affixed to, the ram member 15. Thus a first limit might be defined by the actuating member 14 of switch 11 being depressed as it rides up to a predetermined point on the right-hand inclined surface of cam 16 while a second limit might be defined by the actuating member 13 of switch 10 riding up to a point on the left-hand inclined surface of cam member 16. For a given installation first and second precisely defined mechanical limits as to the position of the ram 15 will define first and second precise locations of the cam member 16 with respect to the fixed position of switches 10 and 11. Since microswitch tolerances introduce variations in the dwell of the actuating members 13 and I4 necessary to effect switch operation, the initial mounting of a pair of such switches at a nominal spacing with respect to one another can only approximately effect switch operations at precisely defined position limits of the ram member 15.

As depicted in FIG. 2, the diagram A illustrates first and second precise ram position limits (and thus cam position limits) defined as limit I and limit 24 The fixed space relationship of switches 10 and II with respect to the cam I6 might typically result in switch actuations at positions labeled SW I" and SW 2." The switch actuation points, SW 1 zuid SW 2, are not symmetrical with respect to the desired limits, Limit 1 and Limit 2, let alone coincident. The mounting mechanism carrying switches 10 and 11 may then be moved axially with respect to the position axis of the ram member 15 to effect symmetry of switch actuation points with respect to the ram member IS to effect symmetry of switch actuation points with respect to the desired mechanical limits. Such a symmetrical arrangement is accordingly arrived at by translating the switch-actuating mechanisms with respect to the position axis of the ram, to attain symmetry between the actual switchoperating points and the desired limits. The symmetrical arrangement is depicted in sketch B of FIG. 2.

Once symmetrical operation, such as depicted in FIG. 2, sketch B, is effected, transverse movement of the switches toward or away from the axis of the ram member I5 will effect respective convergence and divergence of the switch-operating points with respect to the desired limits. Thus, once symmetry is effected by translation of the switches along the axis of the ram member 15, a second adjustment for convergence or divergence as necessary may be effected by moving the switches along an axis transverse that of ram travel to effect switch operations precisely at the desired limit points. The desired relationship is depicted in FIG. 2, waveform C.

Obviously numerous expedients might be employed to cause a pair of fixed space separated microswitches l0 and l I to he moved along mutually perpendicular axes with respect to the ram position axes.

The present invention permits this adjustment with extreme precision in a simple manner employing common hardware.

With reference to FIG. 3, first and second microswitches 10 and. 11 might be carried on respective sides of a generally U- shaped mounting member 12 the relative position of which with respect to fixed plates 18 and I9 is adjustable. FIG. 3 illustrates the axially displaceable rod or ram member IS which carries the linear actuating cam 16 for respective engagements with the actuating member E3 and 14 associated with the microswitches.

The mounting member I2, to which the microswitches I and II are mounted with a fixed space relationship therebetween, is adjustably mounted with respect to the frame member (as depicted by an upper plate I8 and lower plate I9) by means of a clamping setscrew 21 which is adjustable to selectively clamp a projection 22 on mounting member 32 against a projection 20 from base 19, by a first lead screw 24 threadedly received in mounting member 12 and rotatably confined with respect to a second projection 23 from base member 19, and (as shown in FIG. 4) by a second lead screw member 26 rotatably contained within the upper plate member 18 and threadedly received in the switch-mounting member 12. With reference to FIGS. 3 and 4, it is thus seen that with lead screw members 21 and 26 at some predetermined adjusted position and with setscrew member 21 tightened so as to clamp the projection 22 from switchingmounting member 12 against the extension 20 from base 19, the switch-mounting means 12, and thus the switches, bear a fixed relationship with respect to the frame as depicted by the respective upper and lower plate members I3 and 19. The switch-actuating cam 56 carried by the ram 15 is positioned into cooperative engagement with the two switches 10 and II as the rod member assumes defined first and second positions along its actuating axis.

As seen in FIG. 4, the switch members are mounted on the mounting member I2 some predetermined distance between the points of driving engagement of lead screws 12 and 26 with mounting member 12.

ll setscrew 2i is positioned to release the clamping action of the projection 22 from mounting member 12 with respect to the extension from base 19, the positioning of lead screw member 24 will effect a rotation of the cam switch-mounting member 12 about the rotational axis of lead screws 26. The switches, being mounted a predetermined distance from the axis of lead screw 26, follow a slightly arcuate path so as to adjust the position of the switches generally along the axis of the cam-actuating member I5. It is to be realized that in applications for which the present invention is intended that such adjustment are limited in nature and thus, while the switches would follow a somewhat arcuate path, the width of the cam member 16 on rod 135 as depicted in FIG. 4 would be sufficient that the switch-actuating members 13 and 14 would remain in cooperative engagement with the inclined planes which respectively define the cam switch-actuating cam 16 as the respective travel limits of ram 15 were approached and met.

with the desired horizontal adjustment of the switch positions with respect to the cam-actuating member 16 along the axis of the actuator rod 15, the set screw 21 might be adjusted to effect a clamp of the projection 22 from switch-mounting member 12 to the extension 20 from the base 19. A vertical adjustment of the switches with respect to the axis of the cam actuating rod 15 may then be effected by adjustment of lead screw 26 which is threadedly received in the switch-mounting member 12 so as to effect a deflection of switch-mounting member 12 at the point of switch mount, and with respect to the clamping point effected by said screw 21, so as to effect a desired vertical positioning of the switches 10 and II with respect to the surfaces of cam 16.

In operation, the positioning the pair of microswitches 10 and 11 for actuation when the cam member 16 is positioned to first and second precisely defined limits may be effected first by loosening the setscrew member 21 to release the clamping action between the switch-mounting member 12 and the base or frame; second, by adjusting the horizontal positioning of lead screw 24 for symmetry between switch actuation points and the precisely defined mechanical limits of the ram member 15, and third by adjustment of the vertical lead screw 26 for appropriate convergence or divergence of switch actuating points so as to effect precise coincidence between switching actuating points and the precisely defined mechanical limits ofthe ram 15.

FIG. 5 further illustrates the adjustable relationship between the switch-mounting member 12 and the fixed framemounting means as depicted by upper plate member 18, clamping projection 20 and projection 23. FIG. 5 more clearly illustrates the relationship of the extending tab member 22 and mounting means 12. The extension 22 permits a range of rotatable adjustment of mounting means 12 with respect to the frame member while still permitting a clamping relationship to be effected between the mounting means and the base member by means ofsetscrew 21. As previously described, the adjustment procedures for the mounting means of this invention is employed for precise adjustments over a limited range. While the switches I0 and II follow an arcuate path with respect to the fixed base when the horizontal adjustment screw 24 is rotated, the range of adjustment is sufficiently minimal that the arcuate path of the switches permits an operable relationship between the switch actuating members l3 and I4 and the surface of the actuating cam 16 carried on the ram I5 as the position limits are approached and met. The fact that the adjustment is along an arcuate path in no way affects the accuracy of adjustment since the cam surfaces on cam member I6 are inclined plane members. Thus a linear relationship between positioning of ram 15 and the point of actuation of the switches 10 and II is maintained.

It is also apparent with reference to FIG. 5 that vertical adjustment of the switch positions by means of lead screw 26 is accomplished by deformation of the switch-mounting mem bcr I2. The limited adjustment range for which the mechanism is intended permits this simple expedient. Horizontal adjustment by means of lead screw 24, in pivoting the switch-mounting member 12 about the lead screw 26, will effect a slight inter'acting vertical adjustment of the switches with each horizontal adjustment. By use of appropriately pitched lead screws this interaction may be minimized. FIGS. 3 and 4 further illustrate that the lead screw-adjusting members 24 and 26 might be rotatably confined intheir respective mounting members by means of simple hardware including locking nuts and O-ring members which effect a simple implementation of lead screw adjustment which is substantially immune to vibration. Further, while the respective lead screws have been described as being in threaded engagement with the switch mounting member I2, the threaded engagement means might comprise locking nut members captivated in the mounting means I2 to render the adjustment means relatively immune to vibration.

The present invention thus provided by means of simple hardware an adjustable mounting means for a pair of limit switches by means ofwhich symmetry and convergence-divergence adjustments may be readily effected within a limited range in a precise manner.

Although the present invention has been described with respect to a particular embodiment thereof, it is not to be so limited, as changes might be made therein which fall within the scope of the invention as defined in the appended claims.

Iclaim:

1. Means for adjusting a first positionable member with respect to a base member, at least a portion of said base member defining a base plane, said positionable member having at least a portion thereof lying in a plane substantially parallel with respect to said base plane and having a space separated relationship with respect thereto, means for selectively clamping said positionable member to effect a fixed relationship with respect to said base member at a predetermined point on said positionable member, first lead screw means rotatably mounted with respect to said base member and substantially transverse of said base plane, said first lead screw means being threadedly received in said positionable member at a point space separated from said selectively clamped point, and further adjustable mounting means associated with said positionable member and base member for effecting selective rotation of said positionable member about the longitudinal axis of said first lead screw means in a plane substantially parallel that of said base plane in the absence of said aforedefined clamp being effected, adjustment of said first lead screw means with said aforedefined clamp being effected causing a deflection of said positionable member with respect to said base plane, whereby a predetermined point on said positionable member intermediate the axis of said lead screw and said selectively effected clamp point may be positioned respectively parallel to and transverse of said base plane.

2. Positioning means as defined in claim 1 wherein said further adjustable mounting means comprises a second lead screw means rotatably mounted with respect to said base member and along an axis substantially parallel to said base plane, said second lead screw means being threadedly received in said positionable member, rotation of said second lead screw means, in the absence of said aforedefined clamp being effected, rotating said positionable member about the longitudinal axis of said first lead screw means to effect a translation of said positionable member within a plane substantially parallel to said base plane.

3. Positioning means as defined in claim 1 wherein said clamping means comprises a setscrew member threadedly received in said base member and at least a portion of said base member juxtaposed with a side of said positionable member opposite that to which said lead screw member is selectively directable for clamping engagement.

4. Positioning means as defined in claim 2 wherein said clamping means comprises a set screw member threadedly received in said base member and at least a portion of said base member juxtaposed with a side of said positionable member opposite that to which said lead screw member is selectively directable for clamping engagement.

5. Positioning means as defined in claim 1 further comprising switching means including a switch actuating means, said switching means mounted on said positionable member at a selected point lying intermediate the axis of said first lead screw means and said clamping means, a switch-actuating cam member positionable in a plane parallel to said base plane and along an axis transverse that between said clamping means and said first lead screw means, said cam member comprising inclined plane means engageable with said switch actuating means.

6. Positioning means as defined in claim 2 further comprising switching means including a switch-actuating means, said switching means mounted on said positionable member at a selected point lying intermediate the axis of said first lead screw means and said clamping means, a switch-actuating cam member positionable in a plane parallel to said base plane and along an axis transverse that between said clamping means and said first lead screw means, said cam member comprising inclined plane means engageable with said switch-actuating means.

7. Positioning means as defined in claim 5 wherein said switching means comprises first and second switches each actuated by depression of associated actuating means, said first and second switches mounted on said positionable member at a fixed distance either side of the line between said first lead screw means and said clamping means, said switch'actuating cam means comprising a first and second inclined plane camming surfaces and being positionable along an axis transverse the line between said first lead screw means and said clamping means for cooperative engagement between the respective sides thereof and said first and second switch-actuating means respectively, whereby adjustment of said first and second lead screw means respectively effects symmetry and coincidence between the activation of said first and second switches and first and second defined position limits of said camming means along its positioned axis.

8. Positioning means as defined in claim 6 wherein said switching means comprises first and second switches each actuated by depression of associated actuating means, said first and second switches mounted on said positionable member at a fixed distance either side of the line between said first lead screw means and said clamping means, said switch-actuating cam means comprising a first and second inclined plane camming surfaces and being positionable along an axis transverse the line between said first lead screw means and said clamping means for cooperative engagement between the respective sides thereof and said first and second switch actuating means respectively, whereby adjustment of said first and second lead screw means respectively effects symmetry and coincidence between the activation of said first and second switches and first and second defined position limits of said camming means along its positioned axis.

9. Positioning means as defined in claim 3 wherein said lead screw means and said clamping means each comprise frictional means at their respective points of threaded engagement with said base member to resist rotation of said respective members with respect to said base member.

10. Positioning means as defined in claim 4 wherein said lead screw means and said clamping means each comprise frictional means at their respective points of threaded engagement with said base member to resist rotation of said respective members with respect to said base member.

11. Positioning means as defined in claim 7 wherein the dimension of said cam member transverses the position axis thereof permits cooperative engagement with the actuating means associated with said first and second switches throughout a predetermined range of adjustment of said second lead screw means.

12. Positioning means as defined in claim 8 wherein the dimension of said cam member transverses the position axis thereof permits cooperative engagement with the actuating means associated with said first and second switches throughout a predetermined range of adjustment of said second lead screw means. 

1. Means for adjusting a first positionable member with respect to a base member, at least a portion of said base member defining a base plane, said positionable member having at least a portion thereof lying in a plane substantially parallel with respect to said base plane and having a space separated relationship with respect thereto, means for selectively clamping said positionable member to effect a fixed relationship with respect to said base member at a predetermined point on said positionable member, first lead screw means rotatably mounted with respect to said base member and substantially transverse of said base plane, said first lead screw means being threadedly received in said positionable member at a point space separated from said selectively clamped point, and further adjustable mounting means associated with said positionable member and base member for effecting selective rotation of said positionable member about the longitudinal axis of said first lead screw means in a plane substantially parallel that of said base plane in the absence of said aforedefined clamp being effected, adjustment of said first lead screw means with said aforedefined clamp being effected causing a deflection of said positionable member with respect to said base plane, whereby a predetermined point on said positionable member intermediate the axis of said lead screw and said selectively effected clamp point may be positioned respectively parallel to and transverse of said base plane.
 2. Positioning means as defined in claim 1 wherein said further adjustable mounting means comprises a second lead screw means rotatably mounted with respect to said base member and along an axis substantially parallel to said base plane, said second lead screw means being threadedly received in said positionable member, rotation of said second lead screw means, in the absence of said aforedefined clamp being effected, rotating said positionable member about the longitudinal axis of said first lead screw means to effect a translation of said positionable member within a plane substantially parallel to said base plane.
 3. Positioning means as defined in claim 1 wherein said clamping means comprises a setscrew member threadedly received in said base member and at least a portion of said base member juxtaposed with a side of said positionable member opposite that to which said lead screw member is selectively directable for clamping engagement.
 4. Positioning means as defined in claim 2 wherein said clamping means comprises a set screw member threadedly received in said base member and at least a portion of said base member juxtaposed with a side of said positionable member opposite that to which said lead screw member is selectively directable for clamping engagement.
 5. Positioning means as defined in claim 1 further comprising switching means including a switch actuating means, said switching means mounted on said positionable member at a selected point lYing intermediate the axis of said first lead screw means and said clamping means, a switch-actuating cam member positionable in a plane parallel to said base plane and along an axis transverse that between said clamping means and said first lead screw means, said cam member comprising inclined plane means engageable with said switch actuating means.
 6. Positioning means as defined in claim 2 further comprising switching means including a switch-actuating means, said switching means mounted on said positionable member at a selected point lying intermediate the axis of said first lead screw means and said clamping means, a switch-actuating cam member positionable in a plane parallel to said base plane and along an axis transverse that between said clamping means and said first lead screw means, said cam member comprising inclined plane means engageable with said switch-actuating means.
 7. Positioning means as defined in claim 5 wherein said switching means comprises first and second switches each actuated by depression of associated actuating means, said first and second switches mounted on said positionable member at a fixed distance either side of the line between said first lead screw means and said clamping means, said switch-actuating cam means comprising a first and second inclined plane camming surfaces and being positionable along an axis transverse the line between said first lead screw means and said clamping means for cooperative engagement between the respective sides thereof and said first and second switch-actuating means respectively, whereby adjustment of said first and second lead screw means respectively effects symmetry and coincidence between the activation of said first and second switches and first and second defined position limits of said camming means along its positioned axis.
 8. Positioning means as defined in claim 6 wherein said switching means comprises first and second switches each actuated by depression of associated actuating means, said first and second switches mounted on said positionable member at a fixed distance either side of the line between said first lead screw means and said clamping means, said switch-actuating cam means comprising a first and second inclined plane camming surfaces and being positionable along an axis transverse the line between said first lead screw means and said clamping means for cooperative engagement between the respective sides thereof and said first and second switch actuating means respectively, whereby adjustment of said first and second lead screw means respectively effects symmetry and coincidence between the activation of said first and second switches and first and second defined position limits of said camming means along its positioned axis.
 9. Positioning means as defined in claim 3 wherein said lead screw means and said clamping means each comprise frictional means at their respective points of threaded engagement with said base member to resist rotation of said respective members with respect to said base member.
 10. Positioning means as defined in claim 4 wherein said lead screw means and said clamping means each comprise frictional means at their respective points of threaded engagement with said base member to resist rotation of said respective members with respect to said base member.
 11. Positioning means as defined in claim 7 wherein the dimension of said cam member transverses the position axis thereof permits cooperative engagement with the actuating means associated with said first and second switches throughout a predetermined range of adjustment of said second lead screw means.
 12. Positioning means as defined in claim 8 wherein the dimension of said cam member transverses the position axis thereof permits cooperative engagement with the actuating means associated with said first and second switches throughout a predetermined range of adjustment of said second lead screw means. 